To keep white balance simple, it is basically used to get the color of the images as accurate as possible. In some images the colors/subject may look a little off. By off i mean in color they might have a tint of green, blue, yellow, etc. This is often caused because of the lighting. Different lighting causes different results. To adjust white balance you can either use the camera setting or edit in photoshop. The cameras have different preset settings for white balance. Each one is used specifically for a certain moment. However some have the ability to manually adjust the white balance. To manually adjust it your basically telling the camera how the color white looks so it can have a reference point as to how the other colors should look. To do this you can buy a white or grey card specifically used for this or you can find something around you. As long as it fits the colors well.